The new firmware was posted up by XDA Developers forum member Designgears. This update is not the final version that will be rolled out by AT&T later this year therefore the firmware for both versions has its share of bugs and other issues.

The Galaxy S4 has a bug that forces users to reboot their device when playing a video. Users will have to flash a new bootloader if they decide to go through with the upgrade which means they will not be able to return to Android 4.3.

More details on both updates can be found here. The existence of both of these ROMs suggests that the official AT&T update for the Galaxy Note 3 and Galaxy S4 should be rolling out shortly.

A Galaxy Note 3 Android 4.4 KitKat update is already available for T-Mobile, Sprint and Verizon in the form of a new ROM.

CyanogenMod 11 is now available for all of those carrier versions. Users can access the update by downloading the CM11 nightly build. The GSM and AT&T versions have not received the ROMs yet.